Microwave ovens commonly are used to cook food in a rapid and effective manner. To optimize the cooking performance of microwave ovens, various food packaging arrangements have been developed to block, enhance, direct, and otherwise affect microwave interaction with food.
If browning or crisping of the exterior of the food item is desired, the food item is placed in a container that includes a susceptor. The susceptor typically includes a microwave energy interactive material, such as a metal, that absorbs, reflects, and transmits microwave energy in varying proportions. The surface to be browned is placed proximate the susceptor. The susceptor absorbs the microwave energy, and transmits heat to the food item to promote surface browning and crisping. Further, some of the microwave energy is transmitted to the inside of the food item.
Numerous susceptor configurations, shapes, and sizes are known in the art. Depending on the susceptor arrangement, the time of exposure to microwave energy, the desired degree of browning and crisping, and other factors, the susceptor may be in intimate or proximate contact with the food item. Thus, a material or package including a susceptor may be used to cook a food item, and to brown or crisp the surface of the food item in a way similar to conventional frying, baking, or grilling.
One particular food packaging arrangement that may employ susceptors involves closed cells formed between layers of packaging material. Upon exposure to microwave energy, the cells expand to form inflated cells that insulate the food item in the package from the microwave environment. One example of a microwave packaging material that provides inflatable cells is described in International Application Publication No. WO 03/066435A2, published Aug. 14, 2003, which is hereby incorporated by reference herein.
Despite these advances, numerous challenges in microwave cooking remain. For example, removal of large objects from a microwave oven, if not properly supported, can be difficult. If a flat tray supporting a pizza is grasped along only one side and lifted from the oven, the tray might bend and cause the pizza to slide off the tray. Additionally, many packages are fixed in shape and do not provide sufficient intimate or proximate contact with the food item to brown or crisp the surface of the food item. Some packages provide partitions to increase contact with the food item but, in many cases, the shape and size of the partitions are adapted to a standard or nominal food item size that does not accommodate any variation in the size of the food item. For example, if the cross sectional size of a portion of French fries varies, only a portion of the fries will contact the microwave interactive components of the package. Thus, there remains a need for improved microwave energy interactive packages.